Three-dimensional semiconductor memory device

ABSTRACT

A three-dimensional semiconductor memory device may include a first stack block including first stacks arranged in a first direction on a substrate, a second stack block including second stacks arranged in the first direction on the substrate, and a separation structure provided on the substrate between the first stack block and the second stack block. The separation structure may include first mold layers and second mold layers, which are stacked in a vertical direction perpendicular to a top surface of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application claims priority under 35U.S.C. § 119 to Korean Patent Application No. 10-2018-0098149, filed onAug. 22, 2018, in the Korean

Intellectual Property Office, the entire contents of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

The present disclosure relates to a semiconductor memory device and, inparticular, to a three-dimensional semiconductor memory device.

Higher integration of semiconductor memory devices is increasingly usedto satisfy consumer demands for superior performance and inexpensiveprices. In the case of semiconductor memory devices, since theirintegration is an important factor in determining product prices,increased integration is especially demanded. In the case oftwo-dimensional or planar semiconductor memory devices, since theirintegration is mainly determined by the area occupied by a unit memorycell, integration is greatly influenced by the level of a fine patternforming technology. However, the extremely expensive process equipmentneeded to increase pattern fineness sets a practical limitation onincreasing integration for two-dimensional or planar semiconductordevices. To overcome such a limitation, three-dimensional semiconductormemory devices including three-dimensionally arranged memory cells haverecently been proposed.

SUMMARY

Some embodiments provide a three-dimensional semiconductor memory devicehaving a reduced chip size.

According to some embodiments, the disclosure is directed to athree-dimensional semiconductor memory device, comprising: a first stackblock including first stacks arranged in a first direction on asubstrate; a second stack block including second stacks arranged in thefirst direction on the substrate; and a separation structure provided onthe substrate between the first stack block and the second stack block,the separation structure including first mold layers and second moldlayers.

According to some embodiments, the disclosure is directed to athree-dimensional semiconductor memory device, comprising: a first stackand a second stack provided on a substrate to be spaced apart from eachother in a first direction and to extend lengthwise in a seconddirection crossing the first direction; a first bit line crossing thefirst stack and extending lengthwise in the first direction; a secondbit line crossing the second stack and extending lengthwise in the firstdirection, the first and second bit lines being aligned with each otherin the first direction; and a separation structure between the firststack and the second stack, wherein a first side surface of the firststack adjacent to the separation structure and a first side surface ofthe second stack adjacent to the separation structure are perpendicularto a top surface of the substrate.

According to some embodiments, the disclosure is directed to athree-dimensional semiconductor memory device, comprising: stacks on asubstrate; a separation structure on the substrate between the stacks;and a contact structure between the separation structure and each of thestacks.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingbrief description taken in conjunction with the accompanying drawings.The accompanying drawings represent non-limiting, example embodiments asdescribed herein.

FIG. 1 is a circuit diagram schematically illustrating a cell array of athree-dimensional semiconductor memory device according to exampleembodiments.

FIG. 2 is a plan view illustrating a semiconductor wafer including athree-dimensional semiconductor memory device according to exampleembodiments.

FIG. 3 is an enlarged plan view illustrating a semiconductor chip ofFIG. 2.

FIG. 4 is an enlarged plan view illustrating a portion ‘A’ of FIG. 3.

FIG. 5 is a sectional view, which is taken along line I-I′ of FIG. 4, toillustrate a three-dimensional semiconductor memory device according toexample embodiments.

FIG. 6 is a sectional view, which is taken along line II-II′ of FIG. 4to illustrate a three-dimensional semiconductor memory device accordingto example embodiments.

FIG. 7 is an enlarged sectional view illustrating a portion ‘B’ of FIG.5.

FIG. 8 is a sectional view, which is taken along line I-I′ of FIG. 4, toillustrate a three-dimensional semiconductor memory device according toexample embodiments.

FIG. 9 is a sectional view, which is taken along line I-I′ of FIG. 4, toillustrate a three-dimensional semiconductor memory device according toexample embodiments.

FIG. 10 is a sectional view, which is taken along line II-II′ of FIG. 4,to illustrate a three-dimensional semiconductor memory device accordingto example embodiments.

FIG. 11 is an enlarged plan view illustrating the portion ‘A’ of FIG. 3.

FIG. 12 is a sectional view, which is taken along line of FIG. 11, toillustrate a three-dimensional semiconductor memory device according toexample embodiments.

FIG. 13 is an enlarged plan view illustrating the portion ‘A’ of FIG. 3.

FIG. 14 is a sectional view, which is taken along line IV-IV′ of FIG.13, to illustrate a three-dimensional semiconductor memory deviceaccording to example embodiments.

FIG. 15 is an enlarged sectional view illustrating a portion ‘C’ of FIG.14.

FIG. 16 is an enlarged plan view illustrating a semiconductor chip ofFIG. 2.

FIG. 17 is an enlarged plan view illustrating a portion ‘D’ of FIG. 16.

FIG. 18 is an enlarged plan view illustrating the portion ‘D’ of FIG.16.

FIGS. 19A to 22A are sectional views, which are taken along line I-I′ ofFIG. 4 to illustrate a method of fabricating a three-dimensionalsemiconductor memory device according to example embodiments.

FIGS. 19B to 22B are sectional views, which are taken along line II-II′of FIG. 4, to illustrate a method of fabricating a three-dimensionalsemiconductor memory device according to example embodiments.

FIGS. 23 and 24 are sectional views, which are taken along line IV-IV′of FIG. 13, to illustrate a method of fabricating a three-dimensionalsemiconductor memory device according to example embodiments.

It should be noted that these figures are intended to illustrate thegeneral characteristics of methods, structure and/or materials utilizedin certain example embodiments and to supplement the written descriptionprovided below. These drawings are not, however, to scale and may notprecisely reflect the precise structural or performance characteristicsof any given embodiment, and should not be interpreted as defining orlimiting the range of values or properties encompassed by exampleembodiments. For example, the relative thicknesses and positioning ofmolecules, layers, regions and/or structural elements may be reduced orexaggerated for clarity. The use of similar or identical referencenumbers in the various drawings is intended to indicate the presence ofa similar or identical element or feature.

DETAILED DESCRIPTION

FIG. 1 is a circuit diagram schematically illustrating a cell array of athree-dimensional semiconductor memory device according to exampleembodiments.

Referring to FIG. 1, a three-dimensional semiconductor memory device mayinclude a common source line CSL, a plurality of bit lines BL0-BL2, anda plurality of cell strings CSTR between the common source line CSL andthe bit lines BL0-BL2.

The bit lines BL0-BL2 may be two-dimensionally arranged on a substrate,and a plurality of the cell strings CSTR may be electrically connectedin parallel to each of the bit lines BL0-BL2. Accordingly, the cellstrings CSTR may also be two-dimensionally arranged on the common sourceline CSL or the substrate.

Each of the cell strings CSTR may include a ground selection transistorGST connected to the common source line CSL, a string selectiontransistor SST connected to one of the bit lines BL0-BL2, and aplurality of memory cell transistors MCT provided between the ground andstring selection transistors GST and SST. The ground selectiontransistor

GST, the memory cell transistors MCT, and the string selectiontransistor SST constituting each of the cell strings CSTR may beconnected in series. Furthermore, a ground selection line GSL, aplurality of word lines WL0-WL3, and a plurality of string selectionlines SSL0-SSL2 may be provided between the common source line CSL andthe bit lines BL0-BL2 and may be used as gate electrodes of the groundselection transistor GST, the memory cell transistors MCT, and thestring selection transistors SST, respectively.

FIG. 2 is a plan view illustrating a semiconductor wafer including athree-dimensional semiconductor memory device according to exampleembodiments. FIG. 3 is an enlarged plan view illustrating asemiconductor chip of FIG. 2. FIG. 4 is an enlarged plan viewillustrating a portion ‘A’ of FIG. 3. FIG. 5 is a sectional view, whichis taken along line I-I′ of FIG. 4 to illustrate a three-dimensionalsemiconductor memory device according to example embodiments. FIG. 6 isa sectional view, which is taken along line II-IF of FIG. 4 toillustrate a three-dimensional semiconductor memory device according toexample embodiments. FIG. 7 is an enlarged sectional view illustrating aportion ‘B’ of FIG. 5.

Referring to FIGS. 2 and 3, a semiconductor wafer 1000 may include aplurality of unit chips USC. Each unit chip USC may be a semiconductorchip. The unit chips USC may be spaced apart from each other in a firstdirection X and in a second direction Y crossing the first direction X.The semiconductor wafer 1000 may include scribe regions SR1 and SR2defining the unit chips USC. The scribe regions SR1 and SR2 may includea first scribe region SR1 extending in the first direction X and asecond scribe region SR2 extending in the second direction Y.

Each of the unit chips USC may include a substrate 100, blocks BLK1,BLK2, and BLK3, separation structures SRS1, SRS2, and SRS3, and a firstinterlayered insulating layer ILD1. The blocks BLK1, BLK2, and BLK3 maybe provided on the substrate 100. The blocks BLK1, BLK2, and BLK3 may bespaced apart from each other in the second direction Y, on a top surfaceof the substrate 100. The blocks BLK1, BLK2, and BLK3 may include firstto third blocks BLK1, BLK2, and BLK3. The second block BLK2 and thethird block BLK3 may be spaced apart from each other in the seconddirection Y on the substrate 100, and the first block BLK1 may beprovided between the second block BLK2 and the third block BLK3. Thefirst interlayered insulating layer ILD1 may be provided on thesubstrate 100. The first interlayered insulating layer ILD1 may beprovided to cover side surfaces of the blocks BLK1, BLK2, and BLK3 andthe top surface of the substrate 100.

The first to third separation structures SRS1, SRS2, and SRS3 may beprovided on the top surface of the substrate 100. For example, the firstseparation structure SRS1 may be provided on the top surface of thesubstrate 100 to penetrate the first block BLK1 in the third directionZ, which is perpendicular to both the first direction X and the seconddirection Y. The first separation structure SRS1 may include a firstmold structure MS1 and first to fourth separation layers SL1, SL2, SL3,and SL4. The first mold structure MS1 may include a first portion P1 anda second portion P2. The first portion P1 of the first mold structureMS1 may penetrate the first block BLK1 in the third direction Z and mayextend lengthwise in the second direction Y. The second portion P2 ofthe first mold structure MS1 may penetrate the first block BLK1 in thethird direction Z and may extend lengthwise in the first direction X. Anitem, layer, or portion of an item or layer described as extending“lengthwise” in a particular direction has a length in the particulardirection and a width perpendicular to that direction, where the lengthis greater than the width. The first portion P1 and the second portionP2 of the first mold structure MS1 may cross each other. The first blockBLK1 may be divided into first to fourth stack blocks STB1, STB2, STB3,and STB4 by the first mold structure MS1. The first and second stackblocks STB1 and STB2 may be spaced apart from each other in the firstdirection X with the first portion P1 of the first mold structure MS1interposed therebetween, and the third and fourth stack blocks STB3 andSTB4 may be spaced apart from each other in the first direction X withthe first portion P1 of the first mold structure MS1 interposedtherebetween. The first and third stack blocks STB1 and STB3 may bespaced apart from each other in the second direction Y with the secondportion P2 of the first mold structure MS1 interposed therebetween, andthe second and fourth stack blocks STB2 and STB4 may be spaced apartfrom each other in the second direction Y with the second portion P2 ofthe first mold structure MS1 interposed therebetween. The firstseparation layer SL1 may be provided between the first mold structureMS1 and the first stack block STB1, and the second separation layer SL2may be provided between the first mold structure MS1 and the secondstack block STB2. The third separation layer SL3 may be provided betweenthe first mold structure MS1 and the third stack block STB3, and thefourth separation layer SL4 may be provided between the first moldstructure MS1 and the fourth stack block STB4.

The second separation structure SRS2 may be provided on the top surfaceof the substrate 100 to penetrate the second block BLK2 in the thirddirection Z. The second separation structure SRS2 may include a secondmold structure MS2 and fifth and sixth separation layers SL5 and SL6.The second mold structure MS2 may include a first portion P1 and asecond portion P2. The first portion P1 of the second mold structure MS2may penetrate the second block BLK2 in the third direction Z and mayextend lengthwise in the second direction Y. The second portion P2 ofthe second mold structure MS2 may be provided on the top surface of thesubstrate 100 to extend lengthwise in the first direction X along a sidesurface of the second block BLK2. A side surface of the second portionP2 of the second mold structure MS2 may be aligned to a first sidesurface S1 of the substrate 100. The second block BLK2 may be dividedinto fifth and sixth stack blocks STB5 and STB6 by the first portion P1of the second mold structure MS2. The fifth and sixth stack blocks STB5and STB6 may be spaced apart from each other in the first direction Xwith the first portion P1 of the second mold structure MS2 interposedtherebetween. The fifth separation layer SL5 may be provided between thefifth structure block STB5 and the second mold structure MS2, and thesixth separation layer SL6 may be provided between the second moldstructure MS2 and the sixth stack block STB6.

The third separation structure SRS3 may be provided on the top surfaceof the substrate 100 to penetrate the third block BLK3 in the thirddirection Z. The third separation structure SRS3 may include a thirdmold structure MS3 and seventh and eighth separation layers SL7 and SL8.The third mold structure MS3 may include a first portion P1 and a secondportion P2. The first portion P1 of the third mold structure MS3 maypenetrate the third block BLK3 in the third direction Z and may extendlengthwise in the second direction Y. The second portion P2 of the thirdmold structure MS3 may be provided on the top surface of the substrate100 to extend lengthwise along a side surface of the third block BLK3. Aside surface of the second portion P2 of the third mold structure MS3may be aligned to a second side surface S2 of the substrate 100 parallelto the first side surface S1. The third block BLK3 may be divided intoseventh and eighth stack blocks STB7 and STB8 by the first portion P1 ofthe third mold structure MS3. The seventh and eighth stack blocks STB7and STB8 may be spaced apart from each other in the first direction Xwith the first portion P1 of the third mold structure MS3 interposedtherebetween. The seventh separation layer SL7 may be provided betweenthe third mold structure MS3 and the seventh stack block STB7, and theeighth separation layer SL8 may be provided between the third moldstructure MS3 and the eighth stack block STB8.

End portions of each of the first to third mold structures MS1, MS2, andMS3 in contact with the first interlayered insulating layer ILD1 may beprovided to form a staircase structure STS_a (e.g., see FIG. 4). Thefirst to eighth separation layers SL1-SL8 may consist of a single layer.The first separation layer SL1 and the fifth separation layer SL5 eachinclude portions that may extend lengthwise in the second direction Y,may penetrate the first interlayered insulating layer ILD1, and may beconnected to each other. The second separation layer SL2 and the sixthseparation layer SL6 each include portions that may extend in the seconddirection Y, may penetrate the first interlayered insulating layer ILD1,and may be connected to each other. The third separation layer SL3 andthe seventh separation layer SL7 each include portions that may extendin the second direction Y, may penetrate the first interlayeredinsulating layer ILD1, and may be connected to each other. The fourthseparation layer SL4 and the eighth separation layer SL8 each includeportions that may extend in the second direction Y, may penetrate thefirst interlayered insulating layer ILD1, and may be connected to eachother. The first to third separation structures SRS1-SRS3 may have thesame stacking structure. Thus, one (e.g., the first separation structureSRS1) of the first to third separation structures SRS1-SRS3 will beexemplarily described in more detail with reference to FIGS. 3 to 7.

Each of side surfaces of the first to fourth stack blocks STB1-STB4 incontact with the first separation structure SRS1 may be a flat surfacethat is perpendicular to the top surface of the substrate 100 or isparallel to a third direction Z. For example, each of the side surfacesof the first to fourth stack blocks STB1-STB4 in contact with the firstseparation structure SRS1 may be substantially vertical. Each of sidesurfaces of the fifth and sixth stack blocks STB5 and STB6 in contactwith the second separation structure SRS2 may be a flat surface that isperpendicular to the top surface of the substrate 100 or is parallel toa third direction Z. For example, each of the side surfaces of the fifthand sixth stack blocks STB5 and STB6 in contact with the secondseparation structure SRS2 may be substantially vertical. Each of sidesurfaces of the seventh and eighth stack blocks STB7 and STB8 in contactwith the third separation structure SRS3 may be a flat surface that isperpendicular to the top surface of the substrate 100 or is parallel toa third direction Z. For example, each of the side surfaces of theseventh and eighth stack blocks STB7 and STB8 in contact with the thirdseparation structure SRS3 may be substantially vertical.

Each of the first to eighth stack blocks STB1-STB8 may include thestacks ST (e.g., see FIG. 4), which are arranged in the first directionX and extend lengthwise in the second direction Y, and contactstructures 400 a, 400 b, 400 c, 400 d (e.g., see FIG. 4), which areprovided between adjacent ones of the stacks ST and between the stacksST and the separation structures SRS1-SRS3. Some (e.g., STB1-STB4) ofthe first to eighth stack blocks STB1-STB8 will be exemplarily describedin more detail with reference to FIGS. 3 to 7.

Referring to FIGS. 4 to 6, a three-dimensional semiconductor memorydevice may include a lower substrate 200, a peripheral circuit structurePRS, a substrate 100, and first to fourth stacks ST1 a-ST4 a andST1-ST4. The lower substrate 200 may be a silicon substrate, asilicon-germanium substrate, a germanium substrate, or asingle-crystalline epitaxial layer grown on a single-crystalline siliconsubstrate. A device isolation layer 201 may be provided in the lowersubstrate 200. The device isolation layer 201 may define active regionsof the lower substrate 200. The device isolation layer 201 may includean insulating material (e.g., silicon oxide layer).

The peripheral circuit structure PRS may be provided on the lowersubstrate 200. The peripheral circuit structure PRS may include atransistors TR, a peripheral interlayered insulating layer 210,interconnection pads 213, and vias 215. The transistors TR may beprovided on the active regions of the lower substrate 200. Thetransistors TR may include a peripheral gate insulating layer 40, aperipheral gate electrode 50, and source/drain regions 60. Theperipheral interlayered insulating layer 210 may be provided on thelower substrate 200. The peripheral interlayered insulating layer 210may cover the transistors TR. The interconnection pads 213 and the vias215 may be provided in the peripheral interlayered insulating layer 210.The interconnection pads 213 located at different levels may beconnected to each other through the vias 215 therebetween. Furthermore,the transistors TR may be connected to the interconnection pads 213through the vias 215.

The substrate 100 may be provided on the peripheral circuit structurePRS. The substrate 100 may include cell block regions CBR and peripheralregions PR1 and PR2. The cell block regions CBR may be spaced apart fromeach other in the first and second directions X and Y, and theperipheral regions PR1 and PR2 may define the cell block regions CBR.The peripheral regions PR1 and PR2 may include a first peripheral regionPR1 and a second peripheral region PR2. The first separation structureSRS1 may be provided on the first peripheral region PR1. The firstinterlayered insulating layer ILD1 may be provided on the secondperipheral region PR2. The substrate 100 may be formed of or include asemiconductor material (e.g., at least one of silicon (Si), germanium(Ge), silicon germanium (SiGe), gallium arsenide (GaAs), indium galliumarsenide (InGaAs), or aluminum gallium arsenide (AlGaAs)).

The first to fourth stack blocks STB1-STB4 may be provided on the cellblock regions CBR of the substrate 100, respectively. The first stackblock STB1 may be arranged in the first direction X on the top surfaceof the substrate 100 and may include first stacks ST1 a and ST1extending lengthwise in the second direction Y. The second stack blockSTB2 may be arranged in the first direction X on the top surface of thesubstrate 100 and may include second stacks ST2 a and ST2 extendinglengthwise in the second direction Y. The third stack block STB3 may bearranged in the first direction X on the top surface of the substrate100 and may include third stacks ST3 a and ST3 extending lengthwise inthe second direction Y. The fourth stack block STB4 may be arranged inthe first direction X on the top surface of the substrate 100 and mayinclude fourth stacks ST4 a and ST4 extending lengthwise in the seconddirection Y.

Each of the first to fourth stacks ST1 a-ST4 a and ST1-ST4 may includeinsulating patterns 330 and gate electrodes 320 a, 320 b, and 320 c,which are alternately and repeatedly stacked on the substrate 100. Theinsulating patterns 330 may be stacked in the third direction Z. Theinsulating patterns 330 may be formed of or include, for example, asilicon oxide layer. Each of the gate electrodes 320 a, 320 b, and 320 cmay be provided between the insulating patterns 330, which are adjacentto each other in the third direction Z. The gate electrodes 320 a, 320b, and 320 c may include a ground selection gate electrode 320 a, aplurality of cell gate electrodes 320 b, and a string selection gateelectrode 320 c. The ground selection gate electrode 320 a may be thelowermost electrode of the gate electrodes 320 a, 320 b, and 320 c, andthe string selection gate electrode 320 c may be the uppermost electrodeof the gate electrodes 320 a, 320 b, and 320 c. The cell gate electrodes320 b may be provided between the ground selection gate electrode 320 aand the string selection gate electrode 320 c.

End portions of the first to fourth stacks ST1 a-ST4 a and ST1-ST4 incontact with the first interlayered insulating layer ILD1 may beprovided to form a staircase structure STS. For example, a height ofeach of the first to fourth stacks ST1 a-ST4 a and ST1-ST4 may decreasewith increasing distance from the first separation structure SRS1. Forexample, a length, in the second direction Y, of each of the gateelectrodes 320 a, 320 b, and 320 c may decrease incrementally withincreasing distance from the substrate 100. As an example, in thestaircase structure STS of each of the first to fourth stacks ST1 a-ST4a and ST1-ST4, each of the gate electrodes 320 a, 320 b, and 320 c mayhave an end portion. The end portion of each of the ground and cell gateelectrodes 320 a and 320 b may be exposed by another gate electrodedirectly provided thereon. In certain embodiments, an opposite endportion of each of the first to fourth stacks ST1 a-ST4 a and ST1-ST4 incontact with the first separation structure SRS1 may have a wallstructure. The stacks, which are included in the fifth to eighth stackblocks STB5, STB6, STB7, and STB8 of FIG. 3, may have the same stackingstructure as the first to second stacks ST1 a-ST4 a and ST1-ST4.

The first interlayered insulating layer ILD1 may be provided on thesecond peripheral region PR2 of the substrate 100 to cover the staircasestructures STS of the first to fourth stacks ST1 a-ST4 a and ST1-ST4. Atop surface of the first interlayered insulating layer ILD1 may belocated at the same level as top surfaces of the first to fourth stacksST1 a-ST4 a and ST1-ST4. For example, the top surface of the firstinterlayered insulating layer ILD1 may be coplanar with uppermostsurfaces of the first to fourth stacks ST1 a-ST4 a and ST1-ST4. Thefirst interlayered insulating layer ILD1 may be formed of or include,for example, a silicon oxide layer.

Referring to FIGS. 4, 5 and 6, cell vertical channel structures CCS maybe provided on the top surface of the substrate 100 to penetrate thefirst to fourth stacks ST1 a-ST4 a and ST1-ST4 in the third direction Z.The cell vertical channel structures CCS may be spaced apart from thestaircase structures STS of the first to fourth stacks ST1 a-ST4 a andST1-ST4. The cell vertical channel structures CCS may include verticalchannel portions VC, semiconductor pillars SP, charge storing structures340, gap-fill layers 350, and pads 360. The vertical channel portions VCmay be provided to penetrate the first to fourth stacks ST1 a-ST4 a andST1-ST4 in the third direction Z. With respect to a top down view, thevertical channel portions VC may be provided to form a zigzag or in-linearrangement in the first direction X. The vertical channel portions VCmay have a hollow-pipe shape, a cylindrical shape, or a cup shape. Eachof the vertical channel portions VC may include a single layer or aplurality of layers. The vertical channel portions VC may be formed ofor may include, for example, at least one of a single crystallinesilicon layer, an organic semiconductor layer, or nano-sized carbonstructures.

The semiconductor pillars SP may be provided between the verticalchannel portions VC and the substrate 100. The semiconductor pillars SPmay be provided on the top surface of the substrate 100 to penetrate theground selection gate electrode 320 a in the third direction Z. Thesemiconductor pillars SP may be in contact with the vertical channelportions VC, respectively. For example, a top surface of each of thesemiconductor pillars SP may contact a lower portion or surface of eachof the vertical channel portions VC. The semiconductor pillars SP may beformed of a semiconductor layer, whose conductivity type is the same asthat of the substrate 100 or intrinsic. The charge storing structures340 may be provided between the vertical channel portions VC and thegate electrodes 320 a, 320 b, and 320 c. The charge storing structures340 may extend along outer sidewalls of the vertical channel portions VCand in the third direction Z. For example, each of the charge storingstructures 340 may have a shape enclosing an outer sidewall of thevertical channel portion VC. The charge storing structures 340 may beformed of or include, for example, at least one of a silicon oxidelayer, a silicon nitride layer, a silicon oxynitride layer, and high-kdielectric layers and may have a single or multi-layered structure.

As shown in FIG. 7, each of the charge storing structures 340 mayinclude a tunnel insulating layer TL, a blocking insulating layer BLL,and a charge storing layer CTL. The tunnel insulating layer TL may beprovided adjacent to each of the vertical channel portions VC to enclosean outer sidewall of the vertical channel portion VC. The blockinginsulating layer BLL may be provided adjacent to the gate electrodes 320a, 320 b, and 320 c. The charge storing layer CTL may be providedbetween the tunnel insulating layer TL and the blocking insulating layerBLL. The tunnel insulating layer TL may be formed of or include, forexample, at least one of silicon oxide or high-k dielectric materials(e.g., aluminum oxide (Al₂O₃) and hafnium oxide (HfO₂)). The blockinginsulating layer BLL may be formed of or may include, for example, atleast one of silicon oxide or high-k dielectric materials (e.g.,aluminum oxide (Al₂O₃) and hafnium oxide (HfO₂)). The charge storinglayer CTL may be formed of or include, for example, silicon nitride.

The gap-fill layers 350 may be provided in internal spaces defined bythe vertical channel portions VC. The gap-fill layers 350 may be formed,for example, at least one of silicon oxide, silicon nitride, or siliconoxynitride. The pads 360 may be provided on the vertical channelportions VC, the charge storing structures 340, and the gap-fill layers350. The pads 360 may be formed of or include, for example, at least oneof conductive materials or semiconductor materials, which are doped tohave a conductivity type different from that of the vertical channelportions VC.

A gate insulating layer 370 may be provided between each of thesemiconductor pillars SP and the ground selection gate electrode 320 a.The gate insulating layer 370 may have side surfaces, each of which hasan outwardly curved shape. For example, when viewed in cross-section,the gate insulating layer 370 may have an elliptical shape with the longaxis aligned in the vertical direction and the short axis aligned with amiddle line of the adjacent ground selection gate electrode 320 a. Thegate insulating layer 370 may be formed of or may include, for example,an oxide layer formed by a thermal oxidation process.

Dummy channel structures DVS may be provided on the top surface of thesubstrate 100 to penetrate the staircase structures STS of the first tofourth stacks ST1 a-ST4 a and ST1-ST4. The dummy channel structures DVSmay penetrate the end portions of the gate electrodes 320 a, 320 b, and320 c. The dummy channel structures DVS may have substantially the samestructure as the cell vertical channel structures CCS. The structure ofthe dummy channel structures DVS will be described in more detail withreference to FIGS. 11 and 12.

A horizontal insulating layer 380 may be provided between the chargestoring structures 340 and the gate electrodes 320 a, 320 b, and 320 cand may be extended to cover top and bottom surfaces of the gateelectrodes 320 a, 320 b, and 320 c. The horizontal insulating layer 380may be formed of or may include, for example, at least one of siliconoxide (e.g., SiO₂) or high-k dielectric materials (e.g., aluminum oxide(Al₂O₃) and hafnium oxide (HfO₂)).

The first separation structure SRS1 may be provided on the top surfaceof the substrate 100 to be interposed between the first stack ST1 a andthe second stack ST2 a, which are closest to each other in the firstdirection X among the first and second stack blocks STB1 and STB2. Thefirst separation structure SRS1 may also be extended in the firstdirection X to be interposed between the first stacks ST1 and ST1 a andthe third stacks ST3 and ST3 a facing each other in the second directionY. The first separation structure SRS1 may also be extended in the firstdirection X to be interposed between the second stacks ST2 and ST2 a andthe fourth stacks ST4 and ST4 a facing each other in the seconddirection Y. In addition, the first separation structure SRS1 may beextended in the second direction Y to be interposed between the thirdstack ST3 a and the fourth stack ST4 a, which are closest to each otherin the first direction X among the third and fourth stack blocks STB3and STB4. First side surfaces SS1 of the first to fourth stacks ST1a-ST4 a and ST1-ST4, which are parallel to the first direction X, may bein contact with the first separation structure SRS1. A top surface ofthe first separation structure SRS1 may be located at the same level asthe top surfaces of the first to fourth stacks ST1 a-ST4 a and ST1-ST4and the top surface of the first interlayered insulating layer ILD1. Forexample, top surfaces of the first separation structure SRS1, the firstto fourth stacks ST1 a-ST4 a and ST1-ST4, and the first interlayeredinsulating layer ILD1 may be coplanar with one another.

The first separation structure SRS1 may include a mold structure MS andfirst to fourth separation layers SL1, SL2, SL3, and SL4. The moldstructure MS may include first mold layers M1, which are stacked in thethird direction Z, and second mold layers M2, which are respectivelyinterposed between the first mold layers M1. Each of the second moldlayers M2 may be provided between an adjacent pair of the first moldlayers M1, which are adjacent to each other in the third direction Z.Each of the first mold layers M1 may be located at the same level as acorresponding one of the insulating patterns 330, and each of the secondmold layers M2 may be located at the same level as a corresponding oneof the gate electrodes 320 a, 320 b, 320 c. The first mold layers M1 mayinclude a material having an etch selectivity with respect to the secondmold layers M2. For example, the first mold layers M1 may be formed ofor may include a silicon oxide layer, and the second mold layers M2 maybe formed of or may include a silicon nitride layer.

The first separation layer SL1 may be provided between the moldstructure MS and the first stack ST1 a, which is closest to the firstseparation structure SRS1 among the first stacks ST1 and ST1 a, and maybe further extended in the first direction X to be interposed betweenthe mold structure MS and the first side surfaces SS1 of the firststacks ST1 a and ST1. The first separation layer SL1 may be in contactwith the first side surfaces SS1 of the first stacks ST1 a and ST1. Eachof the first side surfaces SS1 of the first stacks ST1 a and ST1 may bea flat surface that is perpendicular to the top surface of the substrate100 or is parallel to the third direction Z. The second separation layerSL2 may be provided between the mold structure MS and the second stackST2 a, which is closest to the first separation structure SRS1 among thesecond stacks ST2 and ST2 a, and may be further extended in the firstdirection X to be interposed between the mold structure MS and the firstside surfaces SS1 of the second stacks ST2 a and ST2. The secondseparation layer SL2 may be in contact with the first side surfaces SS1of the second stacks ST2 a and ST2. Each of the first side surfaces SS1of the second stacks ST2 a and ST2 may be a flat surface that isperpendicular to the top surface of the substrate 100 or is parallel tothe third direction Z.

The third separation layer SL3 may be provided between the moldstructure MS and the third stack ST3 a, which is closest to the firstseparation structure SRS1 among the third stacks ST3 and ST3 a, and maybe further extended in the first direction X to be interposed betweenthe mold structure MS and the first side surfaces SS1 of the thirdstacks ST3 a and ST3. The third separation layer SL3 may be in contactwith the first side surfaces SS1 of the third stacks ST3 a and ST3. Eachof the first side surfaces SS1 of the third stacks ST3 a and ST3 may bea flat surface that is perpendicular to the top surface of the substrate100 or is parallel to the third direction Z. The fourth separation layerSL4 may be provided between the mold structure MS and the fourth stackST4 a, which is closest to the first separation structure SRS1 among thefourth stacks ST4 and ST4 a, and may be further extended in the firstdirection X to be interposed between the mold structure MS and the firstside surfaces SS1 of the fourth stacks ST4 a and ST4. The fourthseparation layer SL4 may be in contact with the first side surfaces SS1of the fourth stacks ST4 a and ST4. Each of the first side surfaces SS1of the fourth stacks ST4 a and ST4 may be a flat surface that isperpendicular to the top surface of the substrate 100 or is parallel tothe third direction Z. The first to fourth separation layers SL1-SL4 mayconsist of a single layer. The first to fourth separation layers SL1-SL4may be formed of or may include, for example, a silicon oxide layer.

In some embodiments, a width W1 of the mold structure MS in the firstdirection X and a width W1′ of the mold structure MS in the seconddirection Y may be substantially equal to a width W2 of each of thefirst to fourth stacks ST1 a-ST4 a and ST1-ST4 in the first direction X(i.e., W1=W2 and W1′=W2). In certain embodiments, the width W1 of themold structure MS in the first direction X and the width W1′ of the moldstructure MS in the second direction Y may be different from the widthW2 of each of the first to fourth stacks ST1 a-ST4 a and ST1-ST4 in thefirst direction X (i.e., W1≠W2 and W1′≠W2).

A second interlayered insulating layer ILD2 may cover the top surfacesof the first to fourth stacks ST1 a-ST4 a and ST1-ST4, the top surfaceof the first interlayered insulating layer ILD1, and the top surface ofthe first separation structure SRS1. The second interlayered insulatinglayer ILD2 may include, for example, a silicon oxide layer.

First to fourth contact structures 400 a, 400 b, 400 c, and 400 d on thetop surface of the substrate 100 may be extended in the third directionZ to penetrate the second interlayered insulating layer ILD2. The firstcontact structures 400 a may be extended lengthwise in the seconddirection Y between adjacent ones of the first stacks ST1 and ST1 a andbetween the first stack ST1 a and the first separation structure SRS1.The second contact structures 400 b may be extended lengthwise in thesecond direction Y between adjacent ones of the second stacks ST2 andST2 a and between the second stack ST2 a and the first separationstructure SRS1. The third contact structures 400 c may be extendedlengthwise in the second direction Y between adjacent ones of the thirdstacks ST3 and ST3 a and between the third stack ST3 a and the firstseparation structure SRS1. The fourth contact structures 400 d may beextended lengthwise in the second direction Y between adjacent ones ofthe fourth stacks ST4 and ST4 a and between the fourth stack ST4 a andthe first separation structure SRS1. The first to fourth contactstructures 400 a, 400 b, 400 c, and 400 d may be in contact with thefirst separation structure SRS1.

In some embodiments, each of second side surfaces SS2 of the first stackST1 a, the second stack ST2 a, the third stack ST3 a, and the fourthstack ST4 a, which are adjacent to the first separation structure SRS1,may be a flat surface that is perpendicular to the top surface of thesubstrate 100. The second side surfaces SS2 of the first to fourthstacks ST1 a-ST4 a may be parallel to the second direction Y. In someembodiments, first to fourth contact structures 400 a, 400 b, 400 c, and400 d may be provided between the first separation structure SRS1 andthe first to fourth stacks ST1 a-ST4 a, respectively. Each of the firstto fourth contact structures 400 a, 400 b, 400 c, and 400 d may be incontact with a corresponding one of the first to fourth separationlayers SL1, SL2, SL3, and SL4 of the first separation structure SRS1 andmay be spaced apart from the mold structure MS of the first separationstructure SRS1. Top surfaces of the first to fourth contact structures400 a, 400 b, 400 c, and 400 d may be coplanar with a top surface of thesecond interlayered insulating layer ILD2.

Each of the first to fourth contact structures 400 a, 400 b, 400 c, and400 d may include a spacer 420 and a common source contact 410. Thecommon source contact 410 may be formed of or may include, for example,at least one of metallic materials (e.g., tungsten, copper, andaluminum) or transition metals (e.g., titanium and tantalum). The spacer420 may be provided to cover a side surface of the common source contact410 or enclose the common source contact 410. The spacer 420 may beformed of or include, for example, at least one of insulating materials(e.g., silicon oxide and silicon nitride).

Common source regions CSR may be provided in the substrate 100 to beoverlapped with the first to fourth contact structures 400 a, 400 b, 400c, and 400 d. The common source regions CSR may be electricallyconnected to the common source contacts 410 of the first to fourthcontact structures 400 a, 400 b, 400 c, and 400 d. The common sourceregions CSR may have a conductivity type different from that of thesubstrate 100.

A third interlayered insulating layer ILD3 may be provided on the secondinterlayered insulating layer ILD2. The third interlayered insulatinglayer ILD3 may cover a top surface of the second interlayered insulatinglayer ILD2 and top surfaces of the first to fourth contact structures400 a, 400 b, 400 c, and 400 d. The third interlayered insulating layerILD3 may be formed of or include, for example, a silicon oxide layer.

Channel contact plugs CCP may be provided on the pads 360. The channelcontact plugs CCP may be provided to penetrate the third interlayeredinsulating layer ILD3 and the second interlayered insulating layer ILD2in the third direction Z and may be connected to the pads 360. Forexample, the channel contact plugs CCP may contact and be electricallyconnected to the pads 360. The channel contact plugs CCP may be formedof or include, for example, at least one of metallic materials (e.g.,copper and tungsten) or metal nitrides (e.g., TiN, TaN, and WN).

Cell contact plugs 510 may be provided on the staircase structures STSof the first to fourth stacks ST1 a-ST4 a and ST1-ST4. For example, thecell contact plugs 510 may be provided on the end portions of the gateelectrodes 320 a, 320 b, and 320 c. The cell contact plugs 510 may beconnected to the gate electrodes 320 a, 320 b, and 320 c. The cellcontact plugs 510 may be formed of or may include, for example, at leastone of metallic materials (e.g., copper and tungsten) or metal nitrides(e.g., TiN, TaN, and WN).

First peripheral contact plugs PCP1 may be provided in the firstseparation structure SRS1. For example, the first peripheral contactplugs PCP1 may be provided to penetrate the third interlayeredinsulating layer ILD3, the second interlayered insulating layer ILD2,the mold structure MS, and the substrate 100 in the third direction Zand may be connected to the interconnection pads 213 of the peripheralcircuit structure PRS. The first peripheral contact plugs PCP1 may beconnected to the transistors TR of the peripheral circuit structure PRS.Second peripheral contact plugs PCP2 may be provided on the secondperipheral region PR2 of the substrate 100. The second peripheralcontact plugs PCP2 may be provided to penetrate the third interlayeredinsulating layer ILD3, the second interlayered insulating layer ILD2,the first interlayered insulating layer ILD1, and the substrate 100 inthe third direction Z and may be connected to the interconnection pads213. The second peripheral contact plugs PCP2 may be connected to thetransistors TR of the peripheral circuit structure PRS.

Although not shown, an insulating layer may be disposed between each ofthe first peripheral contact plugs PCP1 and the substrate 100 anddisposed between each of the second peripheral contact plugs PCP2 andthe substrate 100, insulating the first peripheral contact plugs PCP1and the second peripheral contact plugs PCP2 from the substrate 100. Theeach of the first peripheral contact plugs PCP1 and the each of thesecond peripheral contact plugs PCP2 may be spaced apart from thesubstrate 100 by the insulating layer. Interconnection lines ICN may beprovided on the third interlayered insulating layer ILD3. For example,bottom surface of the interconnection lines ICN may contact a topsurface of the third interlayered insulating layer ILD3. Theinterconnection lines ICN may be connected to the cell contact plugs510, the first peripheral contact plugs PCP1, and the second peripheralcontact plugs PCP2. Bit lines BL1 and BL2 may be provided on the thirdinterlayered insulating layer ILD3. For example, bottom surfaces of thebit lines BL1 and BL2 may contact a top surface of the thirdinterlayered insulating layer ILD3. The bit lines BL1 and BL2 mayinclude first bit lines BL1 crossing the first stacks ST1 and ST1 a,second bit lines BL2 crossing the second stacks ST2 and ST2 a, third bitlines (not shown), crossing the third stacks ST3 and ST3 a, and fourthbit lines (not shown) crossing the fourth stacks ST4 and ST4 a. Thefirst to fourth bit lines BL1 and BL2 may be extended lengthwise in thefirst direction X and may be spaced apart from each other in the seconddirection Y.

The first and second bit lines BL1 and BL2 facing each other in thefirst direction X may be aligned with each other and may be spaced apartfrom each other. In other words, the first and second bit lines BL1 andBL2 may not be electrically connected to each other. The third andfourth bit lines facing each other in the first direction X may bealigned to each other and may be spaced apart from each other. In otherwords, the third and fourth bit lines may not be electrically connectedto each other.

FIG. 8 is a sectional view, which is taken along line I-I′ of FIG. 4 toillustrate a three-dimensional semiconductor memory device according toexample embodiments.

Referring to FIG. 8, the vertical channel portions VC and the chargestoring structures 340 may be in contact with the top surface of thesubstrate 100. That is, the semiconductor pillars SP and the gateinsulating layers 370 described with reference to FIGS. 3 to 7 may beomitted from the three-dimensional semiconductor memory device accordingto the present embodiment.

FIG. 9 is a sectional view, which is taken along line I-I′ of FIG. 4 toillustrate a three-dimensional semiconductor memory device according toexample embodiments of the inventive concept. FIG. 10 is a sectionalview, which is taken along line II-II′ of FIG. 4 to illustrate athree-dimensional semiconductor memory device according to exampleembodiments.

Referring to FIGS. 9 and 10, a transistor TR may be provided on thesecond peripheral region PR2 of the substrate 100. The transistor TR maybe covered with the insulating pattern 330, which is provided betweenthe ground selection gate electrode 320 a and the lowermost cell gateelectrode 320 b and is extended onto the top surface of the secondperipheral region PR2 of the substrate 100. That is, in someembodiments, the lower substrate 200 and the peripheral circuitstructure PRS may be omitted. The first peripheral contact plugs PCP1may not be provided in the first separation structure SRS1. Furthermore,the second peripheral contact plug PCP2 may be provided to penetrate thethird to first interlayered insulating layers ILD1, ILD2, and ILD3 andthe insulating pattern 330, which is provided between the groundselection gate electrode 320 a and the lowermost cell gate electrode 320b, and may be electrically connected to the source/drain regions 60provided in the substrate 100.

FIG. 11 is an enlarged plan view illustrating the portion ‘A’ of FIG. 3.FIG. 12 is a sectional view, which is taken along line III-III′ of FIG.11 to illustrate a three-dimensional semiconductor memory deviceaccording to example embodiments. For concise description, an elementdescribed with reference to FIGS. 3 to 7 may be identified by the samereference number without repeating an overlapping description thereof.

Referring to FIGS. 11 and 12, through insulating patterns TIP may beprovided to penetrate, in the third direction Z, an adjacent pair of thefirst stacks ST1 and ST1 a, an adjacent pair of the second stacks ST2and ST2 a, an adjacent pair of the third stacks ST3 and ST3 a, and anadjacent pair of the fourth stacks ST4 and ST4 a, which are adjacent toeach other in the first direction X. The through insulating patterns TIPmay penetrate the substrate 100 and may be in contact with a top surfaceof the peripheral circuit structure PRS. When viewed in a plan view,each of the through insulating patterns TIP may be provided between thecell contact plug 510, which is connected to the string selection gateelectrode 320 c, and the vertical channel portions VC. Side surfaces ofthe through insulating patterns TIP may be inclined at an angle withrespect to the top surface of the substrate 100. The through insulatingpatterns TIP may be formed of or may include, for example, high-densityplasma (HDP) oxide, tetraethylorthosilicate (TEOS), plasma-enhancedtetraethylorthosilicate (PE-TEOS), O3-tetra ethyl ortho silicate(O3-TEOS), undoped silicate glass (USG), phosphosilicate glass (PSG),borosilicate glass (BSG), borophosphosilicate glass (BPSG), fluoridesilicate glass (FSG), spin on glass (SOG), tonen silazene (TOSZ), or anycombination thereof.

Although not shown, the dummy channel structures DVS may be provided toenclose the through insulating patterns TIP and to penetrate the firstto fourth stacks ST1 a-ST4 a and ST1-ST4 in the third direction Z. Eachof the dummy channel structures DVS may include a dummy semiconductorpillar SP′, a dummy vertical channel portion VC′, a dummy charge storingstructure 340′, a dummy gap-fill layer 350′, and dummy pads 360′. Thechannel contact plugs CCP may not be provided on top surfaces of thepads 360′ of the dummy channel structures DVS. Furthermore, a dummy gateinsulating layer 370′ may be provided between the dummy semiconductorpillar SP′ and the ground selection gate electrode 320 a.

Third peripheral contact plugs PCP3 may be provided to penetrate thethrough insulating patterns TIP and the substrate 100 and may beconnected to the interconnection pads 213 of the peripheral circuitstructure PRS. The third peripheral contact plugs PCP3 may be connectedto the interconnection lines ICN provided on a top surface of the thirdinterlayered insulating layer ILD3.

FIG. 13 is an enlarged plan view illustrating the portion ‘A’ of FIG. 3.FIG. 14 is a sectional view, which is taken along line IV-IV′ of FIG. 13to illustrate a three-dimensional semiconductor memory device accordingto example embodiments. FIG. 15 is an enlarged sectional viewillustrating a portion ‘C’ of FIG. 14. For concise description, anelement described with reference to FIGS. 3 to 7 may be identified bythe same reference number without repeating an overlapping descriptionthereof.

Referring to FIGS. 13 to 15, the first contact structure 400 a betweenthe first stack ST1 a and the first separation structure SRS1, thesecond contact structure 400 b between the second stack ST2 a and thefirst separation structure SRS1, the third contact structure 400 cbetween the third stack ST3 a and the first separation structure SRS1,and the fourth contact structure 400 d between the fourth stack ST4 aand the first separation structure SRS1 may be in direct contact withthe mold structure MS of the first separation structure SRS1. Forexample, in some embodiments, the first to fourth separation layersSL1-SL4 of the first separation structure SRS1 may be omitted. The firstseparation structure SRS1 may include first mold layers M1, which arestacked in the third direction Z on the substrate 100, and second moldlayers M2 and third mold layers M3, which are interposed between thefirst mold layers M1 adjacent to each other in the third direction Z.Side surfaces of the second mold layers M2 may be horizontally recessedfrom side surfaces of the first mold layers M1. For example, widths W3of the second mold layers M2 in the first direction X may be smallerthan widths W4 of the first mold layers M1 in the first direction X(i.e., W3<W4). A sum of the widths W3 of the second mold layers M2 inthe first direction X and a width of the third mold layer M3 in thefirst direction X disposed at the same level from the top surface of thesubstrate may be equal to widths W4 of the first mold layers M1 in thefirst direction X.

In a region between the first mold layers M1 adjacent to each other inthe third direction Z, the third mold layers M3 may be spaced apart fromeach other by each of the second mold layers M2 interposed therebetween.The third mold layers M3 may have side surfaces that are in contact withthe second mold layers M2. The third mold layers M3 may also haveopposite side surfaces that are vertically aligned to the side surfacesof the first mold layers M1. Each of the third mold layers M3 mayinclude an insulating mold layer IML and a metal mold layer MML. Themetal mold layer MML may be placed between the first mold layers M1 thatare adjacent to each other in the third direction Z. The insulating moldlayer IML may be provided between the metal mold layer MML and thesecond mold layer M2 and may be horizontally extended to cover top andbottom surfaces of the metal mold layer MML. For example, the insulatingmold layer IML may have vertical components that cover the side surfacesof the metal mold layer MML and horizontal components that cover top andbottom surfaces of the metal mold layer MML. The insulating mold layerIML may be formed of or may include the same material as the horizontalinsulating layer 380 (e.g., see FIG. 7). The metal mold layer MML may beformed of or may include the same material as the gate electrodes 320 a,320 b, and 320 c. The first peripheral contact plugs PCP1 in the moldstructure MS may be provided to penetrate the first and second moldlayers M1 and M2 and may be spaced apart from the third mold layers M3.For example, the first peripheral contact plugs PCP1 may be providedbetween horizontally adjacent ones of the third mold layers M3.

The mold structure MS may be in contact with the first to fourth stacksST1 a-ST4 a and ST1-ST4. For example, the first to fourth stacks ST1a-ST4 a and ST1-ST4 may be in contact with the first mold layers M1 andthe third mold layers M3 of the mold structure MS. The first to fourthstacks ST1 a-ST4 a and ST1-ST4 may be spaced apart from the second moldlayers M2 of the mold structure MS. In some embodiments, the width W1 ofthe mold structure MS in the first direction X and the width W1′ of themold structure MS in the second direction Y may be larger than thewidths W2 of the first to fourth stacks ST1 a-ST4 a and ST1-ST4 in thefirst direction X (e.g., W1>W2 and W1′>W2).

FIG. 16 is an enlarged plan view illustrating a semiconductor chip ofFIG. 2. FIG. 17 is an enlarged plan view illustrating a portion ‘D’ ofFIG. 16.

Referring to FIGS. 16 and 17, each of the unit chips USC may include thesubstrate 100, first stack blocks STB1 and second stack blocks STB2,which are provided on the top surface of the substrate 100, and thefirst interlayered insulating layer ILD1, which is provided on the topsurface of the substrate 100 to cover side surfaces of the first andsecond stack blocks STB1 and STB2. The first stack blocks STB1 may bespaced apart from each other in the second direction Y, and the secondstack blocks STB2 may be spaced apart from each other in the seconddirection Y. The first stack blocks STB1 and the second stack blocksSTB2 may be provided to face each other in the first direction X.

A separation structure SRS extended lengthwise in the second direction Ymay be provided between the first and second stack blocks STB1 and STB2,which face each other in the first direction X. The separation structureSRS may be provided on the top surface of the substrate 100 to penetratethe first interlayered insulating layer ILD1 in the third direction Z.The separation structure SRS may include the mold structures MS, thefirst separation layer SL1, and the second separation layer SL2. Each ofthe mold structures MS may be provided between the first and secondstack blocks STB1 and STB2 facing each other in the first direction X.The mold structures MS may be spaced apart from each other in the seconddirection Y. The first separation layer SL1 may be extended lengthwisein the second direction Y between each of the mold structures MS andeach of the first stack blocks STB1. The first separation layer SL1 maybe provided on the top surface of the substrate 100 to penetrate thefirst interlayered insulating layer ILD1 in the third direction Z. Thesecond separation layer SL2 may be extended lengthwise in the seconddirection Y between each of the mold structures MS and each of thesecond stack blocks STB2. The second separation layer SL2 may beprovided on the top surface of the substrate 100 to penetrate the firstinterlayered insulating layer ILD1 in the third direction Z. Oppositeends of each of the mold structures MS in contact with the firstinterlayered insulating layer ILD1 may be provided to form the staircasestructures STS_a. The opposite ends of each of the mold structures MSmay be spaced apart from each other in the second direction Y.

Each of the first stack blocks STB1 may include the first stacks ST1 andST1 a, which are spaced apart from each other in the first direction X,and each of the second stack blocks STB2 may include the second stacksST2 and ST2 a, which are spaced apart from each other in the firstdirection X. In some embodiments, each of side surfaces of the first andsecond stack blocks STB1 and STB2 in contact with the separationstructure SRS may be a flat surface that is perpendicular to the topsurface of the substrate 100.

Each of the second side surfaces SS2 of the first stack ST1 a and thesecond stack ST2 a, which are located adjacent to the separationstructure SRS, may be a flat surface that is perpendicular to the topsurface of the substrate 100. The second side surfaces SS2 of the firstand second stacks ST1 a and ST2 a may be parallel to the seconddirection Y and may be in contact with the first and second contactstructures 400 a and 400 b, which are respectively interposed betweenthe separation structure SRS and the first and second stacks ST1 a andST2 a.

According to some embodiments, opposite ends of each of the first andsecond stacks ST1, ST1 a, ST2, and ST2 a in contact with the firstinterlayered insulating layer ILD1 may be provided to form the staircasestructures STS. The opposite ends of each of the first and second stacksST1, ST1 a, ST2, and ST2 a may be spaced apart from each other in thesecond direction Y. In some embodiments, the width W1 of the moldstructure MS in the first direction X may be equal to the width W2 ofeach of the first and second stacks ST1, ST1 a, ST2, and ST2 a in thefirst direction X (i.e., W1=W2). In certain embodiments, the width W1 ofthe mold structure MS in the first direction X may be different from thewidth W2 of each of the first and second stacks ST1, ST1 a, ST2, and ST2a in the first direction X (i.e., W1≠W2).

FIG. 18 is an enlarged plan view illustrating the portion ‘D’ of FIG.16. For concise description, an element described with reference toFIGS. 16 and 17 may be identified by the same reference number withoutrepeating an overlapping description thereof.

Referring to FIG. 18, the first contact structure 400 a between thefirst stack ST1 a and the separation structure SRS may be in directcontact with the mold structure MS of the separation structure SRS, andthe second contact structure 400 b between the second stack ST2 a andthe separation structure SRS may be in direct contact with the moldstructure MS of the separation structure SRS. In other words, in thepresent embodiments, the first separation layer SL1 and the secondseparation layer SL2 may be omitted from the separation structure SRS.

In some embodiments, the width W1 of the mold structure MS in the firstdirection X may be larger than the width W2 of each of the first andsecond stacks ST1, ST1 a, ST2, and ST2 a in the first direction X (i.e.,W1>W2).

FIGS. 19A to 22A are sectional views, which are taken along line I-I′ ofFIG. 4 to illustrate a method of fabricating a three-dimensionalsemiconductor memory device according to example embodiments. FIGS. 19Bto 22B are sectional views, which are taken along line II-IP of FIG. 4to illustrate a method of fabricating a three-dimensional semiconductormemory device according to example embodiments.

Referring to FIGS. 19A and 19B, the device isolation layer 201 may beprovided in the lower substrate 200. The device isolation layer 201 maydefine active regions of the lower substrate 200. The peripheral circuitstructure PRS may be provided on the lower substrate 200. The peripheralcircuit structure PRS may include the transistors TR, theinterconnection pads 213, the vias 215, and the peripheral interlayeredinsulating layer 210. The transistors TR may be formed on the activeregions of the lower substrate 200. The transistors TR may include theperipheral gate insulating layer 40, the peripheral gate electrode 50and the source/drain regions 60. The peripheral interlayered insulatinglayer 210 may be formed on the lower substrate 200. The peripheralinterlayered insulating layer 210 may be formed to cover the transistorsTR. The interconnection pads 213 and the vias 215 may be formed in theperipheral interlayered insulating layer 210.

The substrate 100 may be provided on the peripheral circuit structurePRS. The substrate 100 may include the cell block regions CBR and theperipheral region PR1 and PR2. Mold structures MDS may be formed on thecell block regions CBR of the substrate 100. The mold structures MDS maybe provided on the top surface of the substrate 100 to be spaced apartfrom each other in the second direction Y. The formation of the moldstructures MDS may include alternately and repeatedly forming insulatinglayers 401 and sacrificial layers 403 on the substrate 100. Theinsulating layers 401 may be formed of or include, for example, siliconoxide. The sacrificial layers 403 may be formed of or include, forexample, silicon nitride.

An edge region of each of the mold structures MDS may be patterned toform a staircase structure. The patterning of the mold structure MDS mayinclude forming a mask pattern (not shown) on the mold structure MDS toexpose the edge region of the mold structure MDS, etching the insulatinglayers 401 and the sacrificial layers 403 using the mask pattern as anetch mask, and reducing a width of the mask pattern (not shown) toincrease an planar area of an etch-target layer (e.g., the insulatinglayers 401 and the sacrificial layers 403). In some embodiments, theetching and reducing steps may be repeatedly performed at least twotimes. Top surfaces of end portions of the insulating layers 401 may beexposed in the edge region of the mold structure MDS. An end portion ofthe lowermost layer of the insulating layers 401 may be covered with thelowermost layer of the sacrificial layers 403. Lengths of thesacrificial layers 403 in the second direction Y may decrease withincreasing distance from the substrate 100, and lengths of theinsulating layers 401 in the second direction Y may decrease withincreasing distance from the substrate 100.

The first interlayered insulating layer ILD1 may be formed to cover sidesurfaces of the mold structures MDS and the top surface of the substrate100. For example, the first interlayered insulating layer ILD1 may beformed to cover the staircase structures of the mold structures MDS. Thefirst interlayered insulating layer ILD1 may be formed to expose topsurfaces of the mold structures MDS. For example, the first interlayeredinsulating layer ILD1 may be formed to expose top surfaces of theuppermost ones of the insulating layers 401. The first interlayeredinsulating layer ILD1 may be formed of or may include, for example, atleast one of TEOS oxide or silicon oxide.

Referring to FIGS. 20A and 20B, the first separation layer SL1 and thesecond separation layer SL2 may be formed in each of the mold structuresMDS. The formation of the first separation layer SL1 and the secondseparation layer SL2 may include performing an anisotropic etchingprocess to etch the mold structure MDS and the first interlayeredinsulating layer ILD1 and to form trenches 520 in the mold structure MDSand the first interlayered insulating layer ILD1, filling the trenches520 with an insulating material, and performing a planarization processon the insulating material. In some embodiments, the first and secondseparation layers SL1 and SL2 may be formed through an atomic layerdeposition (ALD) process. The first and second separation layers SL1 andSL2 may be formed of or include, for example, silicon oxide.

The first and second separation layers SL1 and SL2 may be formed todivide each of the mold structures MDS into a first cell mold structureCMS1, a second cell mold structure CMS2, and a remaining mold structureMS between the first and second cell mold structures CMS1 and CMS2. Theremaining mold structure MS may include the first mold layers M1 and thesecond mold layers M2, which are interposed between the first moldlayers M1 adjacent to each other in the third direction Z. The firstmold layers M1 may correspond to portions of the insulating layers 401of the mold structure MDS, and the second mold layers M2 may correspondto portions of the sacrificial layers 403 of the mold structure MDS. Thefirst and second separation layers SL1 and SL2 and the remaining moldstructure MS may constitute the separation structure SRS. In someembodiments, the first and second cell mold structures CMS1 and CMS2 maybe spaced apart from each other in the first and second directions X andY with the separation structure SRS interposed therebetween.

According to some embodiments, the first and second separation layersSL1 and SL2 may be formed in the mold structure MDS to divide the moldstructure MDS in to a plurality of cell mold structures CMS1 and CMS2.In this case, it may be possible to reduce planar areas of the cell moldstructures CMS1 and CMS2, compared with the case of patterning an edgeregion of each of the cell mold structures CMS1 and CMS2 in a staircasestructure. Thus, it may be possible to reduce a size of a finalsemiconductor chip, in which memory elements are three-dimensionallyarranged.

The cell vertical channel structures CCS and the dummy channelstructures DVS (e.g., see FIG. 4) may be formed in each of the first andsecond cell mold structures CMS1 and CMS2. Referring back to FIG. 7, theformation of the cell vertical channel structures

CCS may include forming channel holes CH in each of the first and secondcell mold structures CMS1 and CMS2 and forming the semiconductor pillarSP, the charge storing structure 340, the vertical channel portion VC,the gap-fill layer 350, and the pad 360 in each of the channel holes CH.Referring back to FIG. 12, the formation of the dummy channel structuresDVS may include forming dummy holes (not shown) in each of the first andsecond cell mold structures CMS1 and CMS2 and forming the dummysemiconductor pillar SP′, the dummy charge storing structure 340′, thedummy vertical channel portion VC′, the dummy gap-fill layer 350′, andthe dummy pad 360′ in each of the dummy holes.

The semiconductor pillar SP may be grown from the substrate 100 by aselective epitaxial growth (SEG) process, in which the substrate 100exposed by the channel hole CH is used as a seed layer. The chargestoring structure 340 may be formed on an inner side surface of thechannel hole CH and may cover a portion of the top surface of thesubstrate 100 exposed by the channel hole CH.

Referring back to FIG. 7, the charge storing structure 340 may includethe blocking insulating layer BLL, the charge storing layer CTL, and thetunnel insulating layer TL, which are sequentially formed on the innerside surface of the channel hole CH. The vertical channel portion VC maybe formed to conformally cover an inner side surface of the chargestoring structure 340 and the portion of the top surface of thesubstrate 100 exposed by the charge storing structure 340. The gap-filllayer 350 may be formed in an internal space of the vertical channelportion VC. The gap-fill layer 350 may be formed to fill the remainingempty space of the channel hole CH provided with the vertical channelportion VC. In some embodiments, the gap-fill layer 350 may be formed bya spin-on-glass (SOG) method. The pad 360 may be formed on the verticalchannel portion VC, the charge storing structures 340, and the gap-filllayer 350. A method for forming the dummy channel structures DVS may bethe same as that for the cell vertical channel structures CCS, and thus,a detailed description thereof will be omitted herein.

Referring to FIGS. 21A and 21B, an anisotropic etching process may beperformed on each of the first and second cell mold structures CMS1 andCMS2 to form common source trenches CTH. The formation of the commonsource trenches CTH may include forming the second interlayeredinsulating layer ILD2 on the first and second cell mold structures CMS1and CMS2 and then etching the first and second cell mold structures CMS1and CMS2 using the second interlayered insulating layer ILD2 as an etchmask to expose the top surface of the substrate 100. The common sourcetrenches CTH may be formed to extend lengthwise in the second directionY. The common source trenches CTH may be formed to expose side surfacesof the first and second separation layers SL1 and SL2. As a result ofthe formation of the common source trenches CTH, the stacks ST1 and ST2,which are spaced apart from each other in the first direction X, may beformed on the substrate 100. Each of the stacks ST1 and ST2 may includethe insulating patterns 330 and the sacrificial patterns (not shown).

The sacrificial patterns exposed by the common source trenches CTH maybe removed to form recess regions RR. The sacrificial patterns may beremoved by a wet etching process and/or an isotropic dry etchingprocess. The recess regions RR may be formed between the insulatingpatterns 330 adjacent to each other in the third direction Z. Forexample, the recess regions RR may be formed between horizontallyadjacent ones of the insulating patterns 330. The etching process may beperformed using an etching solution containing phosphoric acid. The gateinsulating layer 370 and the dummy gate insulating layer 370′ (e.g., seeFIG. 12) may be formed on side surfaces of the semiconductor pillar SPand the dummy semiconductor pillar SP′ (e.g., see FIG. 12), which areexposed by the recess regions RR. The gate insulating layer 370 and thedummy gate insulating layer 370′ may be formed of or may include, forexample, a thermally grown oxide layer or a silicon oxide layer.

The horizontal insulating layer 380 (e.g., see FIG. 7) may be formed inthe recess regions RR. For example, the horizontal insulating layer 380may be formed to conformally cover elements exposed by the recessregions RR (e.g., exposed surfaces of the insulating patterns 330, thecharge storing structures 340, the first interlayered insulating layerILD1, the second interlayered insulating layer ILD2, and the first andsecond separation layers SL1 and SL2). The horizontal insulating layer380 may be formed by a deposition process (e.g., CVD or ALD) providing agood step coverage property.

Referring to FIGS. 22A and 22B, the gate electrodes 320 a, 320 b, and330 c may be formed in the recess regions RR, respectively. Theformation of the gate electrodes 320 a, 320 b, and 330 c may includeforming a metal layer to fill the common source trenches CTH and therecess regions RR and removing the metal layer from the common sourcetrenches CTH. The common source regions CSR may be formed in thesubstrate 100 exposed by the common source trenches CTH. The commonsource regions CSR may be formed through an ion implantation process.

The contact structures 400 a and 400 b may be formed in the commonsource trenches CTH. Each of the contact structures 400 a and 400 b mayinclude the spacer 420 and the common source contact 410. The spacer 420may be formed to cover side surfaces of common source trench CTH. Thecommon source contact 410 may be formed to fill a remaining empty spaceof each of the common source trenches CTH provided with the spacer 420.

Referring back to FIGS. 5 and 6, the third interlayered insulating layerILD3 may be formed on the second interlayered insulating layer ILD2. Thethird interlayered insulating layer ILD3 may be formed to cover topsurfaces of the contact structures 400 a and 400 b and the secondinterlayered insulating layer ILD2. The third interlayered insulatinglayer ILD3 may be formed of or may include, for example, a silicon oxidelayer.

The channel contact plugs CCP may be formed on the pads 360, and thecell contact plugs 510 may be formed on the end portions of the gateelectrodes 320 a, 320 b, and 320 c. In addition, the first peripheralcontact plugs PCP1 connected to the transistors TR may be formed in themold structure MS, and the second peripheral contact plugs PCP2connected to the transistors TR may be formed in the first interlayeredinsulating layer ILD1. The channel contact plugs CCP, the cell contactplugs 510, and the first and second peripheral contact plugs PCP1 andPCP2 may be formed of or may include, for example, a metal layer or ametal silicide layer.

The first and second bit lines BL1 and BL2 and the interconnection linesICN may be formed on the third interlayered insulating layer ILD3. Thefirst bit lines BL1 may be formed on the first stack ST1, and the secondbit lines BL2 may be formed on the second stack ST2. The first andsecond bit lines BL1 and BL2 may be electrically connected to thechannel contact plugs CCP, and the interconnection lines ICN may beelectrically connected to the cell contact plugs 510 and the first andsecond peripheral contact plugs PCP1 and PCP2.

FIGS. 23 and 24 are sectional views, which are taken along line IV-IV′of FIG. 13 to illustrate a method of fabricating a three-dimensionalsemiconductor memory device according to example embodiments. Forconcise description, a previously described element or step may beidentified by the same reference number without repeating an overlappingdescription thereof.

Referring to FIG. 23, a process for forming the first separation layerSL1 and the second separation layer SL2 may be omitted. The first andsecond mold layers M1 and M2 may be formed when the mold structure MS isdivided into first and second stacks ST1 and ST2 by the common sourcetrenches CTH formed in the mold structure MS. In this case, widths W5 ofthe first and second mold layers M1 and M2 in the first direction X maybe larger than widths W6 of the first and second stacks ST1 and ST2 inthe first direction X (i.e., W5>W6).

When the recess regions RR are formed by removing the sacrificialpatterns (not shown), separation recess regions SRR may be formedbetween the first mold layers M1, which are adjacent to each other inthe third direction Z, of the separation structure SRS. The separationrecess regions SRR may be extended from the common source trenches CTHto a region between the first mold layers M1 adjacent to each other inthe third direction Z in the first direction X. Since widths of thesecond mold layers M2 of the separation structure SRS are larger thanwidths of sacrificial layers of the first and second stacks ST1 and ST2,the second mold layers M2 of the separation structure SRS may not becompletely removed, even when the sacrificial patterns are completelyremoved. In other words, the second mold layers M2 may remain betweenthe first mold layers M1.

Referring to FIGS. 15 and 24, the third mold layers M3 may be formed inthe separation recess regions SRR, respectively. Each of the third moldlayers M3 may include the insulating mold layer IML and the metal moldlayer MML. The insulating mold layer IML and the horizontal insulatinglayer 380 may be concurrently formed through the same process, and themetal mold layer MML and the gate electrodes 220 a, 220 b, and 220 c mayalso be concurrently formed through the same process.

According to some embodiments, first and second separation layers may beformed in a mold structure to divide the mold structure into a pluralityof cell mold structures. A size of the mold structure may be reduced,compared to the case of patterning an edge region of each of the cellmold structures in a staircase structure. Thus, it may be possible toreduce a size of a final semiconductor chip, in which memory elementsare three-dimensionally arranged.

While example embodiments of the inventive concepts have beenparticularly shown and described, it will be understood by one ofordinary skill in the art that variations in form and detail may be madetherein without departing from the spirit and scope of the attachedclaims.

What is claimed is:
 1. A three-dimensional semiconductor memory device,comprising: a substrate; a stack structure including insulating patternsand gate electrodes, which are alternately and repeatedly stacked on thesubstrate; and a separation structure extending in at least one of afirst direction and a second direction crossing the first direction, anddividing the stack structure, wherein the stack structure has arectangular shape with four side regions, at least one of the sideregions of the stack structure having a staircase structure, wherein theseparation structure extends from one side region of the stack structureto another side region of the stack structure, opposing to the one sideregion, wherein the separation structure includes separation layersextending in a third direction perpendicular to a top surface of thesubstrate and a mold structure between the separation layers, andwherein at least one of end portions of the separation structure has astaircase structure.
 2. The device of claim 1, wherein the moldstructure includes first mold layers which are stacked in the thirddirection, and second mold layers which are interposed between acorresponding pair of the first mold layers adjacent to each other inthe third direction, and wherein the first mold layers and the secondmold layers comprise insulating materials different from each other. 3.The device of claim 2, wherein each of the first mold layers is an oxidelayer, and each of the second mold layers is a nitride layer.
 4. Thedevice of claim 2, wherein the mold structure further includes thirdmold layers which are provided between the first mold layers adjacent toeach other in the third direction and are horizontally spaced apart fromeach other by respective one of the second mold layers interposedtherebetween.
 5. The device of claim 4, wherein each of the third moldlayers has a side surface which is in contact with the one of the secondmold layers, and an opposite side surface which is aligned to sidesurfaces of the first mold layers.
 6. The device of claim 1, wherein theseparation structure extends in the first direction and the seconddirection, and divides the stack structure into first to fourth stackblocks, the separation structure including a first portion extendinglengthwise in the first direction and a second portion extendinglengthwise in the second direction, wherein the first portion of theseparation structure is disposed between the first stack block and thesecond stack block, and between the third stack block and the fourthstack block, and wherein the second portion of the separation structureis disposed between the first stack block and the third stack block, andbetween the second stack block and the fourth stack block.
 7. The deviceof claim 6, wherein the separation layers include first to fourthseparation layers, and wherein the first separation layer is between thefirst stack block and the mold structure, the second separation layer isbetween the second stack block and the mold structure, the thirdseparation layer is between the third stack block and the moldstructure, the fourth separation layer is between the fourth stack blockand the mold structure.
 8. The device of claim 7, wherein each of thefirst to fourth separation layers comprises a single layer.
 9. Thedevice of claim 6, wherein each of the first to fourth stack blocksincludes a plurality of stacks extending lengthwise in the seconddirection and being spaced apart from each other in the first direction,and wherein a width of the separation structure in the first directionis larger than a width of each of the plurality of stacks in the firstdirection.
 10. The device of claim 6, further comprising: a contactstructure between the separation structure and each of the first tofourth stack blocks, wherein the separation structure is in contact withthe contact structure.
 11. The device of claim 1, further comprising: alower substrate provided below the substrate; a peripheral circuitstructure provided between the substrate and the lower substrate, theperipheral circuit structure including a peripheral circuit transistor;and a plurality of through insulating patterns penetrating the stackstructure and the substrate.
 12. A three-dimensional semiconductormemory device, comprising: a substrate; a stack structure includinginsulating patterns and gate electrodes, which are alternately andrepeatedly stacked on the substrate; a separation structure extending inat least one of a first direction and a second direction crossing thefirst direction, and dividing the stack structure, a lower substrateprovided below the substrate; a peripheral circuit structure providedbetween the substrate and the lower substrate, the peripheral circuitstructure including a peripheral circuit transistor; and a peripheralcontact plug penetrating the separation structure and the substrate, andelectrically connected to the peripheral circuit transistor of theperipheral circuit structure, wherein the stack structure has arectangular shape with four side regions, at least one of the sideregions of the stack structure having a staircase structure, wherein theseparation structure extends from one side region of the stack structureto another side region of the stack structure, opposing to the one sideregion, wherein the separation structure includes separation layersextending in a third direction perpendicular to a top surface of thesubstrate and a mold structure between the separation layers, andwherein at least one of end portions of the separation structure has astaircase structure.
 13. The device of claim 12, wherein the moldstructure includes first mold layers and second mold layers, which arealternately and repeatedly stacked on the substrate, wherein each of thefirst mold layers is located at the same level as a corresponding one ofthe insulating patterns, wherein each of the second mold layers islocated at the same level as a corresponding one of the gate electrodes,and wherein the first mold layers and the second mold layers compriseinsulating materials different from each other.
 14. The device of claim13, wherein the peripheral contact plug penetrates the first and secondmold layers of the mold structure, and wherein the peripheral contactplug is horizontally spaced apart from the separation layers.
 15. Thedevice of claim 12, wherein the separation structure extends in thefirst direction and the second direction, and divides the stackstructure into first to fourth stack blocks, the separation structureincluding a first portion extending lengthwise in the first directionand a second portion extending lengthwise in the second direction,wherein the first portion of the separation structure is disposedbetween the first stack block and the second stack block, and betweenthe third stack block and the fourth stack block, and wherein the secondportion of the separation structure is disposed between the first stackblock and the third stack block, and between the second stack block andthe fourth stack block.
 16. The device of claim 15, further comprising:a contact structure extending lengthwise in the second direction betweenthe separation structure and each of the first to fourth stack blocks,wherein each of the separation layers of the separation structure is incontact with the contact structure.
 17. A three-dimensionalsemiconductor memory device, comprising: a block disposed on asubstrate; and a separation structure dividing the block into first tofourth stack blocks, the separation structure having a cross shape andincluding a first portion extending lengthwise in a first direction anda second portion extending lengthwise in a second directionperpendicular to the first direction, wherein at least a portion of anedge region of the block has a staircase structure, wherein theseparation structure includes separation layers and a mold structurebetween the separation layers, and wherein at least one of end portionsof the separation structure has a staircase structure.
 18. The device ofclaim 17, further comprising: an interlayered insulating layer providedon the substrate to cover the staircase structure of the block and thestaircase structure of the separation structure, wherein the separationlayers are extended into the interlayered insulating layer.
 19. Thedevice of claim 17, wherein the mold structure includes first moldlayers and second mold layers, which comprising insulating materialsdifferent from each other, wherein the first mold layers are stacked ina vertical direction perpendicular to a top surface of the substrate,and wherein each of the second mold layers is interposed between acorresponding pair of the first mold layers adjacent to each other inthe vertical direction.
 20. The device of claim 19, wherein the moldstructure further includes metal mold layers, which are provided betweenthe first mold layers adjacent to each other in the vertical directionand are horizontally spaced apart from each other by each of the secondmold layers interposed therebetween.